WASHINGTON — The widening gap between the wealthiest Americans and everyone else has made the economy more prone to boom-bust cycles and slowed the 5-year-old recovery from the recession, rating agency Standard & Poor’s said in a report Tuesday.

The rising concentration of income among the top 1 percent of earners has contributed to S&P’s cutting its growth estimates for the economy. In part because of the disparity, it estimates that the economy will grow at a 2.5 percent annual pace in the next decade, down from a forecast five years ago of a 2.8 percent rate.